case sensitive in MS SQL

[TheBao]

I have a table (USERINFO) in MSSQL database with 2 columns: USR, PWD

Let say I have 1 record: ABC, ****

Now when I perform these:
Select * from USERINFO where USR = "ABC"
Select * from USERINFO where USR = "aBc"
.....
I always get 1 record. How do I compare the string case sensitive so that only

Select * from USERINFO where USR = "ABC"

will return 1 record.

Thanks.